New 30 Year Climate Normals

Updated Climate Normals

NOAA's National Climatic Data Center (NCDC) released the 1981-2010 Normals on July 1, 2011. On August 1st, 2011, the next 30 year interval of normals will start to be used in NWS climate products.  The new normals will use a data period from 1981 to 2010, replacing the old period of 1971-2000. 

Click here for graphs that show how the new Normals have adjusted at Duluth, MN. Similar graphs for other locations will be available soon. The main difference is that the decade of the 1970s is no longer in the 30-year average set. One thing to keep in mind is that for the Northland, the 70s was a generally cool decade. 

Additional Normals products; such as frost/freeze dates, growing degree days, population-weighting heating and cooling degree days, and climate division and gridded normals; will be provided in a supplemental release by the end of 2011.

NOAA's new 1981-2010 Climate Normals are now available on the internet via File Transfer Protocol (ftp). You can access the new normals from the NCDC normals website at:  1981-2010 Climate Data from NCDC
What is a climate "Normal"
A climate normal in general is an average of 30 years of data. Every ten years the National Weather Service recalculates the normals using the next interval of 30 years.  On August 1st, 2011, the next interval of 30 year normals will become officail. The new normals will use a data period from 1981 to 2010, replacing the old period of 1971-2000. 

Example of a climate normal:
The normal temperature for a specific day (ex. July 4th) is calculated by taking the average temperature during the day of every July 4th for all 30 years between 1981 and 2010.
Why are there Two sets of Climate Records for Duluth?

The NOAA Climate Services has published an article detailing the impacts that changes in our climate have had, and may have in the future.
 Adjusted Maximum Temperatures Normals
  Adjusted Minimum Temperatures Normals

NOAA is the premier source of Weather, Water and Climate information. For local information contact the NWS in Duluth at 218-729-6697 or contact

Kevin, Climate Services Focal Point at
For general questions about Normals or help accessing the 1971 - 2000 product, please contact NCDC's User Engagement & Services Branch at 828-271-4800, option 2. For questions regarding the development of the 1981 - 2010 Normals, please contact Anthony Arguez.

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